Update gitaly to 0.100.0 required for gitlab 10.8

[mfechner]

Summary

Commit message:
Update gitaly to 0.100.0 required for gitlab 10.8

Test Plan

All patches are build, you can find all build logs:
https://pkg.fechner.net/jail.html?mastername=111amd64-gitlab

The fresh packages are tested against a new installation using:
https://gitlab.fechner.net/mfechner/Gitlab-vagrant

An old version is updated following the manual:
https://gitlab.fechner.net/mfechner/Gitlab-docu

[mat]

Could you use devel/arcanist, or at least generate a diff with full context like it does, with svn diff -x -U9999 or git diff -U9999.

[mfechner]

Updated diff as asked.

[swills]

Approved